Modern hybrid and electric vehicles are highly dependent on a high voltage battery to provide energy to and store energy from an electric machine. The capability of a battery pack may become reduced over time. This reduction in capability may be the result of irreversible physical and chemical changes within the battery and may be a function of how the battery is operated and stored. These reductions in capability may result in the battery having less energy storage capacity and power than the battery might have had when new. Reductions in battery capability and power due to aging and operation may impact vehicle performance.
It may be desirable to estimate the remaining amount of useful life of the battery pack. Prediction of the degradation that a battery pack has experienced may allow a controller to modify the battery pack operating limits accordingly. Measuring the remaining life of a battery pack is useful during the design phase to ensure that a battery pack can meet specified requirements. In addition, measuring the remaining life of a battery pack may have useful service aspects. In general, knowledge of the remaining life of a battery pack during development and production may aid in reducing warranty costs and service issues.